Belt grinder

ABSTRACT

A belt grinder includes a drive motor with a main drive wheel and a return wheel, over which a grinding belt passes. The turn around wheel has an external diameter in line with the outer diameter of the main drive wheel so that the belt tracks along a straight-line section between the two wheels.

FIELD OF THE INVENTION

The present invention relates to a belt grinder particularly but not exclusively a connector for a roller cartridge for the belt grinder.

BACKGROUND OF THE INVENTION

A belt grinder includes a drive motor with a main drive wheel and a return wheel, over which a grinding belt passes. The turn around wheel has an external diameter in line with the outer diameter of the main drive wheel so that the belt tracks along a straight-line section between the two wheels.

A platen can be mounted behind the belt along the straight-line section to accommodate flat grinding onto the belt. The drive wheel is formed with a larger diameter wheel compared to the return wheel so that the belt has different dimensioned radii for grinding different curvatures, as required.

A portable belt grinder generally has the return wheel mounted on an axle of a bracket that is fixed relative to a supporting arm so that the wheel cannot be replaced or swapped in the event a different diameter return wheel might be needed.

International Patent Application Number PCTAU01/00616 discloses a belt grinder mounted on a stand, where the return wheel is mounted in a rotatable carriage. The carriage is provided with a series of return wheels of different diameters to match the required grinding needs. If a return wheel of a different diameter is needed, the carriage is simply rotated in order to select the relevant wheel and the carriage is then locked in place.

Another mechanism for changing the return wheel of a stand-mounted grinder is to present the return wheel in a cartridge and to releasable mount the cartridge to a supporting arm. One mounting arrangement has two vertical slots formed in a back plate of the cartridge. The cartridge is slid down over mounting pins provided on the arm and then secured is place with a bolt or the like that is fixed in place, through an elongate aperture that runs parallel to the slots. As may be appreciated, there might be a degree of misalignment of the roller if the back plate is not properly located, which might easily be the case if debris or contaminants have clogged or fouled the slots.

Another mounting arrangement is to provide a peg on the rear of the plate with a flat section machined on top, for receipt in a corresponding shaped hole in the supporting arm, after which a grub screw or the like is used to fix the peg relative to the hole. However, machining tolerance between the hole and the peg may result in a degree of play and some misalignment of the return wheel may again result, especially if debris or contaminants work in between the flat of the peg and the hole.

In any event, such mounting arrangements are susceptible to a degree of misalignment and are in fact somewhat difficult to secure since the fixing screw or bolt needs to be fastened with an additional tool while the cartridge is held in place.

Misalignment of the return wheel is problematic as the belt that passes over the wheel will be subject to slide or drift across the wheel and that could in turn render the grinder unsuitable for grinding.

OBJECT OF THE INVENTION

The present invention seeks to provide an improved mechanism for fixing a cartridge in a belt grinder.

SUMMARY OF THE INVENTION

In accordance with the invention, there is provided a belt grinder including a connector with a latch arranged to effect a 3-dimensional lock on a cartridge carrying a return roller of the grinder.

Preferably, the connecter includes a cradle for receiving and locking the cartridge in place. Preferably, the cartridge is defined by side members arranged either side of the roller and a cross piece for receipt in the cradle.

Preferably, the cradle includes laterally spaced contact surfaces to engage with the cartridge.

Preferably, the cradle has a curved profile to fit the crosspiece.

Preferably, the profile is formed as a part-cylinder.

Preferably, the connector includes a jaw against which the piece abuts in the locked position.

Preferably, the latch is spring biased and serves to lock the cartridge against pitch, yaw and roll movement relative to the arm.

Preferably, the crosspiece of the cartridge is rotated into connection with the cradle so as to wipe the contact surfaces clear of contaminants prior to locking the cartridge in place.

Preferably, the side members are arranged to project beyond the crosspiece to register against end sections of the cradle and inhibit any lateral movement of the cartridge.

Preferably, the cartridge is adapted to be loaded into the cradle with one hand and snap locked in place.

In another aspect, there is provided a cartridge for a belt grinder including two side members supporting a roller and a crosspiece with a part-cylinder shaped profile arranged for receipt in a cradle with a corresponding profile.

In another aspect, there is provide a method of loading the above described cartridge into a cradle including rotating the cartridge into a locked position and snap latching the cartridge in place so as to provide a 3-dimensional lock between the cartridge and the cradle.

Preferably, the method includes wiping contact surfaces of the cradle with the crosspiece as the cartridge in rotated into the cradle, in order to remove contaminants.

Preferably, the method further includes engaging end sections of the cradle with the side members in order to prevent lateral movement of the cartridge in the cradle.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is more fully described, by way of non-limiting example only, with reference to the accompanying drawings, in which:

FIG. 1 is a side view of a belt grinder;

FIG. 2 is an enlarged view of a connector and cartridge of the belt grinder;

FIG. 3 is a perspective view of the connector and cartridge;

FIG. 4 is a perspective view of the connector;

FIG. 5 is a side view of the connector;

FIG. 6 a is a perspective view of a large dimension roller;

FIG. 6 b is a perspective view of a mid-sized dimension roller; and

FIG. 6 c is a perspective view of a small dimension roller.

DETAILED DESCRIPTION OF THE DRAWINGS

Referring firstly to FIG. 1, a belt grinder 1 is shown mounted on a stand 2. The grinder can be rotated relative to the stand in a clockwise or anticlockwise direction as viewed until positioned in a preferred orientation and then locked in place by an adjustment handle 3.

The grinder 1 includes a motor casing 4 and connected framework 5 that supports a tension roller 6 and an extension arm 7 that carries a return roller 8.

A grinding belt 9 passes around the return roller 8, tension roller 6 and a main drive roller (not shown) mounted inside the casing 4. During operation, the belt 9 is driven at high speed and the different sized diameters of the return roller 8 and the drive roller can be utilized for grinding purposes, as required.

The casing 4 has a hinged panel 10 that can be opened to allow the belt 9 to be removed, if needed.

The tension roller 6 serves to provide appropriate tension to the belt 9. The tension roller 6 is mounted to a linkage 11 that is connected to the framework via a spring 12. The spring 12 maintains pressure on the belt 9 by pressing the roller 6 against the belt 9. If the belt 9 needs to be changed, the tension roller 6 can be manually forced away from the belt 9, against the bias of the spring 12, and temporarily locked out of engagement until the belt 9 is replaced.

The panel 10 can also be opened during operation to allow access to the main roller for curved-surface grinding.

The arm 7 also supports a platen 13 that is mounted to the arm 7 via a bracket 14, for flat grinding. The platen 13 is parallel to the belt 9 along a straight section 15 of the belt 9 between the casing 4 and the return roller 8. The platen 13 provides support to allow for flat grinding against the belt 9. An outer diameter 16 of the return roller 8 needs to be aligned relative to the platen 13, in order to maintain the parallel relationship of the belt 9 and platen 13.

A spark shield 17 is fitted over the return roller 8. The shield 17 is mounted to the arm 7 by a hinge 18. If access to the return roller 8 is needed, such as for smaller diameter curved surface grinding, the shield 17 is simply pivoted out of the way.

The return roller 8 is mounted to the arm 7 via a cartridge 19 that is locked into a connector 20. The connector 20 includes a snap latch 21 that is pivotally mounted to the arm 7 and biased into the locked position by a spring 22.

The connector 20 is shown in more detail in FIG. 2 as including a cradle 23 fitted to the arm 7. The latch 21 includes an elongate lever 24 that extends between the spring 22 and a pivot mounting 25, and a retaining finger 26 which projects across the cradle 23 to capture the cartridge 19 in the cradle 23.

Referring now to FIG. 3, the cartridge 19 is more clearly shown as including two side members 27 that support the roller 8 and a cross piece 28. The piece 28 preferably has a part-cylindrical profile that nests inside the cradle 23 and the side members 27 register with end sections 29 of the cradle 23 so that the cartridge 19 is securely located in the cradle 23 and prevented from lateral movement as well as from roll movement relative to the cradle 23, about an elongate axis “X”.

When fixed in position, the piece 28 also abuts against a lower jaw 30 of the cradle 23 and the finger 26 clamps the piece 28 against the jaw 30 to secure the cartridge 19 from pitching about an axis “Y” and yaw movement about an axis “Z”.

As such, the connector 20 and cartridge 19 are fixed together in a 3-dimensional locked arrangement.

Referring now to FIGS. 4 and 5, the cradle 23 preferably has a curved profile 30 in the form of a part-cylinder to match the piece 28 of the cartridge 19. The curved profile has an advantage in so far as the profile is easy to machine and allows for a reliable and close fit with the cartridge 19.

The cradle 23 is formed with raised side cheeks 32 that define contact surfaces 33 for engaging the piece 27. In order to fit the cartridge 19 in the connector 20, the lever 24 is depressed against the bias of the spring 22 and the piece 28 is rotated into the cradle 23 until the piece abuts the jaw 31. The rotating action causes the piece 28 to wipe the contact surfaces 33 of the cradle 23 during insertion so as to clear the surfaces 33 of contaminants. As the cartridge 19 is rotated in place, the lever 24 can be released so that the latch 21 snap fits into place when the cartridge 19 is fully loaded into the cradle 23, to provide a positive lock between the cartridge 19 and the cradle 23.

To remove the cartridge 19, the latch 21 is simply opened and the cartridge 19 rotated out of the cradle 23. Another cartridge 19 can then be swapped in.

FIGS. 6 a to 6 c show three different forms of cartridge 19, with different diameter rollers 8. The orientation of the crosspiece 28 relative the side members 27 will vary depending on the diameter of the roller 8, in order to ensure the outer diameter 16 of the roller 8 maintains the relative alignment with the platen 13.

As may be appreciated, the connector 20 and cartridge 19 of the invention allows a roller 8 to be held in a reliable 3-dimensional locked position. The cartridge 19 can be easily swapped in or out of the grinder 1, as required. For example, the latch 21 can be actuated with one hand and the cartridge 19 can be replaced with the other hand. Accordingly, the cartridge 19 can itself be swapped in or out with single hand use once the latch is opened and no additional tools are required.

The invention has been described by way on non-limiting example only and many modifications and variations can be made without departing from the spirit and scope of the invention. The use and inter-relationship of the connector 20 and cartridge 19 may, for example, have application to other belt driven devices aside from a belt grinder mounted on a stand, such as a portable or hand held belt grinder or sander device or the like where there is a need to swap in different roller cartridges and reliable lock such cartridges in a fixed orientation relative to the device.

LIST OF PARTS

1. Belt grinder

2. Stand

3. Handle

4. Casing

5. Framework

6. Tension roller

7. Arm

8. Return roller

9. Belt

10. Panel

11. Linkage

12. Spring

13. Platen

14. Bracket

15. Section

16. Outer diameter

17. Shield

18. Hinge

19. Cartridge

20. Connector

21. Latch

22. Spring

23. Cradle

24. Lever

25. Pivot mounting

26. Finger

27. Side members

28. Piece

29. Sections

30. Profile

31. Jaw

32. Cheeks

33. Contact surfaces 

1. A belt grinder including a connector with a latch arranged to effect a 3-dimensional on a cartridge carrying a return roller of the grinder.
 2. The belt grinder of claim 1, wherein the connector includes a cradle for receiving and locking the cartridge in place and wherein the cartridge is defined by side members arranged either side of the roller and a cross piece for mounting the cartridge in the cradle.
 3. The belt grinder of claim 2, wherein the cradle includes laterally spaced contact surfaces to engage with the cartridge.
 4. The belt grinder of claim 3, wherein the cradle has a carved profile to fit the crosspiece.
 5. The belt grinder of claim 4, wherein the profile is formed as a part-cylinder.
 6. The belt grinder of claim 3, wherein the connector includes a jaw against which the piece abuts in the locked position.
 7. The belt grinder of claim 6, wherein the latch is spring biased and serves to lock the cartridge against pitch, yaw and roll movement relative to the arm.
 8. The belt grinder of claim 7, wherein the crosspiece of the cartridge is rotated into connection with the cradle so as to wipe the contact surfaces clear of contaminants prior to locking the cartridge in place.
 9. The belt grinder of claim 8, wherein the side members are arranged to project beyond the crosspiece to register against end sections of the cradle and inhibit any lateral movement of the cartridge.
 10. The belt grinder of claim 9, wherein the cartridge is adapted to be loaded into the cradle with one hand and snap locked in place.
 11. A cartridge for a belt grinder including two side members supporting a roller and a crosspiece with a part-cylinder shaped profile arranged for receipt in a cradle with a corresponding profile.
 12. A method of loading the cartridge of claim 11 into a cradle including rotating the cartridge into a locked position and snap latching the cartridge in place so as to provide a 3-dimensional lock between the cartridge and the cradle.
 13. The method of claim 12, including wiping contact surfaces of the cradle with the crosspiece as the cartridge in rotated into the cradle, in order to remove contaminants.
 14. The method of claim 13, further including engaging end sections of the cradle with the side members in order to prevent lateral movement of the cartridge in the cradle. 